When are SAP Calculations for Conversions Required?

SAP Calculations are a necessary part of the planning process for new builds and extensions, but what about conversions? In this article, we go over whether SAP calculations are required for conversions, what a good SAP score is, and how to improve it, if necessary. 

So, when are SAP calculations for conversions required? SAP calculations are required for conversions when you significantly change the use of the building or room. You will need a new SAP calculation on the converted room or dwelling to demonstrate how energy efficient it is. 

Read on to learn more about SAP calculations for conversions. 

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Do I Need a SAP Calculation for a Conversion?

SAP calculations are required when a room or dwelling is significantly changed, or the intended use of the room or dwelling is changed. In these cases, a new SAP calculation is required to determine the new energy efficiency status. This comes under ‘Material Change of Use’ or ‘Change of Energy Status’, as stated in Part L1B of the Building Regulations.

When are SAP Calculations for Conversions Required?

There are two circumstances when SAP calculations for conversions are required;

Material Change of Use

Material change of use is when there is a significant change in the intended use of a room or dwelling. For example,

  • When, after conversion, the building is used as a dwelling when it was not originally built for that purpose.
  • When, after the conversion, the building now contains a flat, when it previously did not.
  • When, after the conversion, the number of dwelling units in a building has changed. 

Changing a building in such ways will likely affect the energy status of the building, thus requiring a new SAP calculation.

Change of Energy Status

A change in energy status occurs when a previously unheated building is designed to be heated in the future via conversion. It’s likely that material change of use will also be applicable here.

Why are SAP Calculations Required?

A SAP calculation is the government adopted methodology for calculating energy performance in domestic properties. It was introduced into Building Regulations (Part L1B) in 1995, and is a vital step towards improving the energy performance of buildings, and reducing CO2 emissions.

The previous government made a legally binding commitment to reduce CO2 and greenhouse gas emissions by 80% by 2050.  As a result of this, more stringent regulations around building emissions are now in force.

What is a Good SAP Rating for a Conversion?

Essentially, the higher the SAP score, the better. SAP calculations run from 1-100, with 100 being the best, and anything over 100 indicating that a building is actually exporting energy. 

SAP scores inform the more widely known EPC rating (A-G). A SAP score of 92-100 would equate to an EPC rating of A. 81-91 equates to an EPC rating of B, and 69-80 equates to a C rating. EPC ratings from A-C are generally regarded as good. 

EPC ratings below C generally require improvement as they are not very energy efficient. In fact, in rented accommodation, landlords are legally not permitted to rent their property if it has an EPC below E.

SAP ScoreEPC Rating
92-100A
91-91B
69-80C
55-68D
39-54E
21-38F
1-20G

How Do You Pass a SAP Calculation on a Conversion?

One main key piece of advice when trying to pass a SAP calculation is to not begin designing your conversion until your SAP has been authorised since, if it does not conform with Part L of Building Regulations, any alterations or repairs to a property will be costly and time-consuming.

To pass a SAP assessment, you must take into account:

  • Materials used
  • The efficiency of heating systems
  • The level of thermal insulation used
  • The use of renewable energy
  • The fuel used for water, space heating, light, and ventilation
  • Air leakage and solar gains found through openings in the property
  •  C02 emissions

As well as this, the following actions should also help to pass a SAP assessment:

  • Install double glazing
  • Install loft, floor, and wall insulation
  • Replace old boilers
  • Install a secondary heating source such as a working fireplace

How Do I Increase my SAP Score on my Conversion?

If your initial SAP calculation is a little lower than you’d like, the following advice should help you to increase the SAP score of your conversion:

  • Get your SAP calculation completed before the construction phase
  • Invest in the good building fabric
  • Consider ways to lower the thermal mass
  • Consider  renewable energy
  • Insulate walls, floors, and lofts
  • Enhance your heating controls
  • Use low-energy light bulbs

You can also find individual recommendations for increasing your conversion’s energy efficiency on your EPC certificate.

SAP Calculations for Conversions

RS energy are SAP calculation and energy compliance experts. We provide SAP calculations for a wide range of clients on conversions, new builds, and extensions. As accredited SAP assessors, we’re here to support you through the process of making your property more energy-efficient, both in the design and build phases. 

Get in touch with us today to learn more about our SAP calculation service.